start fixing cov for trie

[Eikix]

closes #678

[Eikix]

will investigate the rest of the missing lines, it's unclear whether they are not covered or just bugged

[codecov]

Codecov Report

Attention: Patch coverage is 50.00000% with 2 lines in your changes missing coverage. Please review.

Project coverage is 66.44%. Comparing base (bee0671) to head (e2868e6).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
cairo/ethereum/cancun/trie.cairo	50.00%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #692   +/-   ##
=======================================
  Coverage   66.44%   66.44%           
=======================================
  Files          88       88           
  Lines       20433    20435    +2     
=======================================
+ Hits        13577    13579    +2     
  Misses       6856     6856           

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[Eikix]

looks like the coverage report is mostly ";"
i can't find single blocks of code not covered

tbd once we fix coverage report with debug_info